It is highly desirable to minimize the average time that it takes for each gear to run through a gear burnishing machine to burnish the gear and to remove scale after heat treatment, but prior to gear inspection. However, the amount of burnishing action that must take place on each gear is determined by the nature of the gear and the required burnishing action is a predetermined factor. Therefore, in order to minimize the average burnishing time, it is necessary to provide a multiple gear burnishing system with an overlapping burnishing cycle so the loading and unloading times for the gears consumes only a minor portion of the entire burnishing cycle, and such loading and unloading occurs for one gear while another gear is being burnished. One solution to this problem is to provide an index drive for multiple gears, but an index drive machine is overly complicated and expensive. For example, a four-station index drive operating on a six-second cycle could provide twelve seconds of burnishing per gear, but this would require four sets of expendable burnishing gears.
In the gear burnishing system of the present invention, by contrast, a shuttle mechanism is employed instead of an index drive, wherein the first fed gear that is fed to the burnishing machine is pushed to one of two gear burnishing stations and the next gear is fed to the other station in an alternating manner. A rotating cam controls the vertical displacement of support tables for the ring gear workpieces and the gear engagement means which causes meshing of the burnishing gears at each station with their associated ring gear. This loading technique allows burnishing to continue on one gear while the other is being loaded or unloaded. In addition, only two sets of expendable gear burnishing machines are required for a two-station gear burnishing machine which is much less complicated and expensive than a four-station index drive machine with a comparable average gear burnishing time.
In the present invention, a brake/clutch mechanism may be employed to stop the rotation of the control cam so that a dwell time can be provided wherein both gears may be burnished for a period of time longer than it takes for the control cam to complete a complete revolution, thereby allowing the burnishing time for each ring gear workpiece to be adjustable by control of the dwell time of the brake/clutch arrangement.
A gear burnishing engagement mechanism, for the machine of the present invention, employs a pair of pressure rollers at each burnishing station, that are each approximately in line of the center line of one burnishing gear and the center line of the ring gear. The pressure distribution applied by the pressure rollers to the ring gears in this manner, thus minimizes distortion of the shape of the ring gear.